In the original version of Scrum, the commitment of the team for the sprint is dependent on two things: a good work ethic and good estimates. If either one is an issue, then the work won't be done on time. The “no commitment required” title of my previous post was a bit tongue in cheek. Absolutely commitment is important, but I don’t think that making it part of “Scrum” will suddenly make team members with a poor work ethic suddenly have a good work ethic or team members with problems estimating better at estimating. Nor will having commitment part of Scrum automatically improve a bad team/PO dynamic.

People with a good work ethic will work hard. If you have folks with a poor work ethic, I believe Agile will expose this more clearly and then you can use your management skills to address it one way or another. Hopefully, with a win-win solution.

Estimates are just that, estimates. They are a good-faith representation of what the team believes it will take with the information they have at hand. When something is discovered, then it is important for the team to communicate that to the PO, but I don’t think it means that they have to stick to the original estimate. Is that “letting them off the hook?” I don’t think so. Let’s face it, if they estimate 8 hours, but it turns out to take 24, the only way to do it in 8 is to do 8 hours “on the books” and 16 hours off. To have the team absorb those extra 16 hours means that they will have to take it out of their own time which is violating the idea of sustainable pace.

If you have a team that consistently misses their estimates, that’s something different. Missing estimates should be the exception rather than the rule. When it becomes the rule, the question is what’s going on? Is team morale low? Why?

When using story points combined with tracking velocity, there shouldn't be a problem with estimates because story points and velocity should make the issue of estimates a moot point. What I mean is that if all estimates are suddenly off by a factor, the result is simply that velocity goes down. If estimates have always been "off" then velocity will not be going up or down, it will just be fairly constant. Since story points and velocity are relative, estimates that are "off" by a factor aren't a real problem.

Instead, the “problem” may be manifesting itself more as a general feeling of “this team just doesn’t seem to be as productive as it could be.” But then you are back to “why not?” I don’t think an enforced framework of commitment will change anything if the team has, for instance, low morale.

On the other hand, if the problem is wildly varying velocity (perhaps due to wildly varying accuracy of estimating stories) then I would venture there is a good chance that the stories are just too big in general and a good remedy to consider is to aggressively split stories into smaller stories.